Sub-intimal dissector and methods for performing endarterectomies therewith

ABSTRACT

A sub-intimal dissector and methods for performing endarterectomies therewith in which the said dissector comprises an elongated shape-retaining, bendable shaft, a dissecting tip on one end of the shaft, the tip being arcuate transverse to its longitudinal axis, a slightly forwardly convex leading edge of the tip smoothly merging with opposed side edges which taper rearwardly and inwardly to the shaft, the leading edge and the side edges being smoothly rounded between the top and bottom surfaces of the tip, the arcuately longest portion of the convex bottom of the tip being equal to approximately between one fifth and one third of the circumference of the artery upon which the instrument is employed; the method including the steps of longitudinally incising the artery to expose the diseased intima; transversely incising the artery to gain access to the interface of the intima and media; intruding the leading edge of the dissector tip intermediate the intima and media, passing the tip longitudinally along the artery intermediate to the intima and media with a steady forward pressure to detach the intima from the media by a wedging action for the length of the shaft inserted; withdrawing the dissecting tip to the position of entry and repeating the procedure with the remaining portions of the circumference of the artery; sequentially each newly dissected portion preferably being immediately adjacent to and contiguous with the previously dissected portion; incising the artery distially at a distance from the proximal incision no greater than approximately twice the length of the shaft and repeating the aforesaid dissecting procedure to disengage the intima from the media; and removing the dissected intima through one of the incisions.

United States Patent Curi Dec. 30, 1975 SUB-INTIMAL DISSECTOR ANDMETHODS being arcuate transverse to its longitudinal axis, a FORPERFORMING ENDARTERECTOMIES slightly forwardly convex leading edge ofthe tip THEREWITH smoothly merging with opposed side edges which taperrearwardly and inwardly to the shaft, the leading [76] inventor g gggCourt Roseland edge and the side edges being smoothly rounded betweenthe top and bottom surfaces of the tip, the arcu- [22] Filed: July 18,1973 ately longest portion of the convex bottom of the tip [21] Appl.No.: 380,508

Primary Examiner-Channing L. Pace Attorney, Agent, or FirmBain,Gilfillan & Rhodes [57] ABSTRACT A sub-intimal dissector and methods forperforming endarterectomies therewith in which the said dissectorcomprises an elongated shape-retaining, bendable shaft, a dissecting tipon one end of the shaft, the tip being equal to approximately betweenone fifth and one third of the circumference of the artery upon whichthe instrument is employed; the method including the steps oflongitudinally incising the artery to expose the diseased intima;transversely incising the artery to gain access to the interface of theintima and media; intruding the leading edge of the dissector tipintermediate the intima and media, passing the tip longitudinally alongthe artery intermediate to the intima and media with a steady forwardpressure to detach the intima from the media by a wedging action for thelength of the shaft inserted; withdrawing the dissecting tip to theposition of entry and repeating the procedure with the remainingportions of the circumference of the artery; sequentially each newlydissected portion preferably being immediately adjacent to andcontiguous with the previously dissected portion; incising the arterydistially at a distance from the proximal incision no greater thanapproximately twice the length of the shaft and repeating the aforesaiddissecting procedure to disengage the intima from the media; andremoving the dissected intima through one of the incisions.

8 Claims, 4 Drawing Figures U.S. Patent Dec. 30, 1975 3,929,138

FIG.1

SUB-INTIMAL DISSECTOR AND METHODS FOR PERFORMING ENDARTERECTOMIESTHEREWITH BACKGROUND OF THE INVENTION In arterial sclerotic disease, theintima thickens until functional occlusion occurs. The solution lies inone of two expedients; the arterial graft or the arterial endarterectomywherein the disease intima is removed or reduced to restore flow throughthe artery. The arterial graft has produced ambivalent and inconclusiveresults in the past.

Formerly, a conventional endarterectomy involved incising the artery forthe full length of the occlusion; removing the obstructing intima andclosing the incision by a running arterial suture. This procedure issufficiently time consuming and traumatic so as to be unsuitable for theaged or infirm.

More recently, instruments have been devised to strip the diseasedintima from the artery by the intrusion of a cutting instrument througha relatively small incision thereby avoiding the longitudinal incisionextending for the length of the obstruction. The most widely accepted ofsuch instruments is shown in U.S. Pat. No. 2,944,552 and comprises anannular cutting ring on one end of an elongated shaft. While the ringcould be made in a variety of sizes, its use is frequently attended byeither or both the failure to remove all of the intima or the cutting ofthe media. Additionally, even in the hands of the most experiencedsurgeons, there is very little feel or control of the instrument.

Another device which has received limited acceptance is the gas needlesuch as shown in U.S. Pat. No. 3,481,338 or 3,525,339. As in the case ofthe annular cutting ring, the gas needle frequently traumatizes themedia, leaving a residue of the diseased intima and provides the surgeonwith virtually no feel or control.

The present invention contemplates the stripping of the diseased intimaby means of a wedging or separating action as distinguished from acutting action by use of a smoothly rounded dissecting tip on the end ofa bendable shaft.

Additionally, the present invention comtemplates stripping the intimausually in a continuous longitudinal segment by use of a dissecting tip,arcuately transverse to the longitudinal axis of the shaft to define anupper concave surface and a lower convex surface, the longest portionthereof extending for a distance equal to approximately one third to onefifth of the circumference of the artery and preferably one quarter ofthe circumference of the artery.

SUMMARY OF THE INVENTION A sub-intimal dissector comprising an elongatedshaft, the shaft being bendable and having shape memory; a dissectingtip on the end of the shaft; the tip being arcuate transverse to itslongitudinal axis to define a concave top surface and convex bottomsurface extending between side edges; a slightly forwardly convexleading edge on the tip smoothly merging with the said opposed sideedges; the opposed side edges tapering rearwardly and inwardly towardthe shaft from a position slightly rearwardly of the leading edge; thearcuately longest portion of the said convex bottom surface extendingalong an arc transverse to the longitudinal axis of the tip approximtelyone third to one fifth of the circumference of the artery upon which itis ing surface, substantially free from corrosive attack by A method forperforming endartectomies comprising incising an artery to expose theinterface between the intima and the media; intruding a dissecting tipintermediate the intima and the media; the dissecting tip being arc uateto define a concave top surface and a conforming convex bottom surface,the arc of the tip being generally transverse to the longitudinal axisof movement of the tip and extending a maximum distance equal to no morethan approximately one third and no less than approximately one fifth ofthe circumference of the artery; passing the tip longitudinally throughthe artery from the said incision along the interface of the intima andmedia for a distance; withdrawing the tip to the incision; reintrud-ingthe tip between the intima and media successively along arcuate pathscontiguous to previous paths of movement of the tip for said distanceuntil substantially the entire intima is disengaged from the media alongsaid distance; and withdrawing the disengaged intima from the artery.

PREFERRED EMBODIMENT OF THE INVENTION The aforesaid objects andadvantages as well as other objects and advantages may be achieved byuse of the methods and instruments claimed herein preferred embodimentsof which are described below.

A preferred embodiment of a sub-intimal dissector is illustrated in thedrawings in which:

FIG. 1 is a top plan view of a sub-intimal dissector;

FIG. 2 is an end elevational view of the dissector shown in FIG 1;

FIG. 3 is a view in perspective of the sub-intimal dissector intrudedbetween the intima and the media in an artery;

FIG. 4 is an end elevational cross sectional view of an artery showingarcuate planes of dissection between the media and the intima generatedby use of the subintimal dissector illustrated in FIGS. 1, 2 and 3.

Referring now to the drawings in detail, the sub-intimal dissectorcomprises a smoothly rounded shaft 11 fabricated of a malleable metal soas to be limitedly resiliently flexible and bendable to retain a bentconfiguration yet sufficiently strong to transmit forces from a handle12 through the shaft 11 to a dissecting tip 13 even when bent.

The handle 12 is preferably flat and sufficiently large to provide forfascicle manipulation although the particular shape of the handle is amatter of choice.

The dissecting tip 13 is formed on the end of the shaft 1 l opposite thehandle 12 and comprises a concave top surface 14 and a generallyconforming convex bottom surface 15 the arc of curvature beingtransverse to the longitudinal axis of the shaft 11 when the shaft 11 isaxially straight.

The dissecting tip 13 is provided with a leading edge which is slightlyforwardly convex in a direction opposite the shaft 11. The leading edge16 smoothly merges with the opposed side edges 17 and 18 of the tip 13.The opposed side edges 17 and 18 preferably have a section, respectively19 and 20 parallel to the longitudinal axis of the tip 13 for arelatively short distance and then a tapering section, respectively 21and 22 which tapers rearwardly and inwardly to the shaft 11. The

shaft 1 1 is relatively rigid from the tip 13 rearwardly for a shortdistance to insure that the shaft 11 does not flex at the point ofjuncture between it and the tip 13.

The leading edge 16 and the side edges 17 and 18 of thetip 13 aresmoothly rounded along their entire length between the concave topsurface 14 and the convex bottom surface 15. The sub-intimal dissectoris provided in varying sizes according to the size of the artery uponwhich it is to be employed. The most important relative dimension is thegreatest arcuate distance along the concave-convex portions of the tip13 which lie between the parallel portions 19 and of the side edges 17and 18. The distance should be equal to between approximately one thirdto one fifth of the circumference of the artery upon which the dissectoris to be employed; a distance equal to one quarter of said circumferencebeing preferable.

The thickness of the tip 13 between the top surface 14 and the bottomsurface 16 is between approximately 0.50 millimeter and 1.00 millimeterdepending upon the size of the artery. It is also preferable to maintainthe parallel portions 19 and 20 of the side edges 17 and 18 as short asis functionally consistent with insuring separation of the intima fromthe media in order to minimize trauma to the media incident upon movingcontact with the said side edges. Preferably, the parallel side edges 19and 20 should range between 0.5 cm and 1.0 cm depending upon the arcdistance between the parallel side edges.

Previous instruments have employed cutting edges to separate the intimafrom the media. This has resulted in either trauma to the media or aseverance of only a portion of the intima leaving a residue.Functionally, the object of the present invention is to wedge the intimafrom the media without substantial cutting action. To this end, theleading edge 16 and the side edges 17 and 18 are smoothly roundedbetween the top surface 14 and bottom surface 15. Additionally, theleading edge 16 is slightly forwardly convex and smoothly merges withthe side edges 17 and 18 so as to avoid sharp edges, points or otherabrupt configurational characteristics which tend to cut or inducetrauma.

Still further, the tip 13 and the shaft 11 are provided with alubricating cladding such as tetrafluoroethylene which is resistant tocorrosive attack by body chemicals. Such a lubricating cladding enhancesthe wedging action of the tip 13 and reduces the damage of trauma to themedia.

The following is a table of preferred sizes for the dissector accordingto artery size.

4 been previously established both proximal and distal control of theartery by clamping.

The arteriotomy is heldapart with various surgical devices.

A transverse incision is made at the arteriotomy to and through theintima surface to provide access to a clear, clean plane of dissection.Once an adequate plane of dissection has been developed between theintima and media, the sub-intimal dissector as described above isintruded between the intima and the media after being properly moistenedwith normal saline. When the instrument is moved downwardly along theartery, the intima is wedged away from the media along an arc equal toor slightly greater than the arc between the parallel side portions 19and 20 of the dissector tip. The dissector is forced gently forwardly ina relatively slow, steady and continuous fashion. The surgeon has aconsiderable degree of both control and feel as the dissector tip passesdown the artery to detect any loss of the dissection paths.

After the dissector has been intruded preferably to the full length ofthe shaft, the dissector is withdrawn to the original incision. Thedissector is then intruded between the media and intima in a pathsadjacent to the plane initially disengaged.

This procedure is repeated for as many times as is necessary to developpaths of dissection around the circumference of the interface of theintima and the media.

After completion of the dissection around, the interface between themedia and the intima, another arteriotomy is performed distially to theocclusion. The arteriotomy is made in the same fashion together with atransverse incision to gain access to the zone between the intima andthe media.

The same procedure as described above is performed again pushing orforcing the dissecting tip forwardly along the artery until the firstdissected portion is reached. The distance between the distal andproximal arteryectomies which includes the occluded portion is nogreater than twice the length of the shaft of the sub-intimal dissector.Thus, the tip intruded from the proximal incision will engage thedissection made through the distal incision.

After the entire occluded intima has been dissected from the media theentire specimen is withdrawn by grasping with forceps and removingthrough one of the incisions.

In order to avoid damage to the media, the dissecting tip is providedwith no sharp cutting edges and has TABLE I ARTERY SHAFT TIP OVERALL TIPSHAFT DIAMETER LENGTH THICKNESS LENGTH DIAMETER 2 mm 6 in. 0.50 mm 0.5cm I mm 4 mm 6 in. 0.50 mm 0.8 cm 1 mm 6 mm 8-12 in. 1.00 mm 1.0 cm 1.5mm 8 mm 8-12 in. 1.00 mm 1.2 cm 1.5 mm 10 mm 8-10 in. 1.00 mm 1.5 cm 1.5mm

The method comprises the following steps.

An arteriotomy is performed by making an incision in the artery wall.The incision is longitudinal to the axis of the artery for a distance offrom 2m 6 cm in length depending upon existing conditions and the sizeof the artery. This is to gain entrance to the internal portions of theartery. As in the usual arteriotomy there has 3 ,929 l 3 8 5 to beconstrued to include a dissection of the media from the adventitia.

The foregoing description is merely intended to illustrate an embodimentof the invention. The component c. a portion of the shaft immediatelyrearwardly of the tipis sufficiently rigid to prevent significantflexure at the junction of the tip and shaft, and

d. the tip is provided with an extremely low friction parts have beenshown and described. They each may 5 Surface d have substitutes whichmay perform a substantially for performmg en artefectomles C msimilarfunction; such substitutes may be known as pnsmg' a. incising an arteryto expose the interface between the intima and the media, 10 intruding adissecting tip intermediate the intima and proper substitutes for thesaid components and may have actually been known or invented before thepresent invention.

What is claimed is;

1. A sub-intimal dissector comprising:

a. an elongated shaft, the shaft being bendable and having shape memory,

the media at said exposed interface,

c. wedging the intima and media apart by passing the dissecting tiplongitudinally along said interface for a distance from said incisionwhile avoiding damag- 5 ing the integrity of both the intima and media,b. a dissecting tip on one end of the shaft, (1. withdrawing thedissecting tip longitudinally to the c. the tip being arcuate transverseto its longitudinal incision,

axis to define a concave top surface and a convex e. reintruding thedissecting tip intermediate the inbQttQm urface extending between ideedges tima and media and the intima and media d. a slightly forwardlyconvex leading edge on the tip apart as affeSa1d successively along p fsmoothly merging with the said opposed side edges, ous to Prevlous Pathsof movement f l f e. the opposed side edges tapering rearwardl and saiddistance until substantially the entire intima 1s inwardly toward theshaft from a position slightly wedged f the fnedla m Sald dlstance andrearwardly of the leading edge f. withdrawing the disengaged intima fromthe artery. f. the arcuately longest portion of the said convex p gg forperforming endarterectomles combottom i exteridmg aloilg arc transversea. the procedure in accordance with claim 6 includto the longitudinalaxis of the tip a distance equal to ing approxlmately one thud to fi hthe clrcum' b. the steps of wedging the intima from the media by ferenceof an artery upon whlch to be passing along said interface a dissectingtip having p y and a concave top surface and a conforming convex theSald lead1ng edge both Sald pp slde bottom surface; the arc of the saidtip being generedges i g smoothly founded between the C011- allytransverse to the longitudinal axis of movement Ca tOp and Convex bottomurfa f the tipof the said tip and extending an arcuate distance 2. Asub-intima] dissector comprising, equal to approximately one third toone fifth of the a. the structure in accordance with claim 1, andcircumference of the artery; the said tip having a b. the said tip beingprovided with an extremely low slightly forwardly convex leading edgesmoothly f i ti f e merging with opposed side edges; the leading edges 3A Sub intima1 dissector comprising and both side edges being smoothlyrounded bea. the structure in accordance with claim 1, in which, tweenthe p and bottcfm Surfacesb. the said opposed side edges are parallelfor a rela- A method for performmg endarterectomles tivel short distanceimmediatel rearwardl of the Pnsmg: Said llleading edge y y a. theprocedure in accordance with claim 6, and the A Sub-intima dissectorcomprising b ir i i sifi the arter to ex ose interfaces between a. thestructure in accordance with claim 1', in which, g y p b. a portion ofthe shaft immediately rearwardly of the top is sufficiently rigid toprevent significant flexure at the junction of the tip and shaft.

5. A sub-intimal dissector comprising,

the intima and media both distal and proximal to an occlusion, and

c. wedging the intima and media apart by passing the dissecting tiplongitudinally along said interface as aforesaid from both the distaland proximal incia. the Structure in accordance with claim in which,sions in the direction of the opposite incision until b. the saidopposed side edges are parallel for a relath ath of di engagement fromthe respective tively short distance immediately rearwardly of theincisions engage. said leading edge,

1. A sub-intimal dissector comprising: a. an elongated shaft, the shaftbeing bendable and having shape memory, b. a dissecting tip on one endof the shaft, c. the tip being arcuate transverse to its longitudinAlaxis to define a concave top surface and a convex bottom surfaceextending between side edges, d. a slightly forwardly convex leadingedge on the tip smoothly merging with the said opposed side edges, e.the opposed side edges tapering rearwardly and inwardly toward the shaftfrom a position slightly rearwardly of the leading edge, f. thearcuately longest portion of the said convex bottom surface extendingalong an arc transverse to the longitudinal axis of the tip a distanceequal to approximately one third to one fifth of the circumference of anartery upon which it is to be employed, and g. the said leading edge inboth said opposed side edges being smoothly rounded between the concavetop and convex bottom surface of the tip.
 2. A sub-intimal dissectorcomprising, a. the structure in accordance with claim 1, and b. the saidtip being provided with an extremely low friction surface.
 3. Asub-intimal dissector comprising, a. the structure in accordance withclaim 1, in which, b. the said opposed side edges are parallel for arelatively short distance immediately rearwardly of the said leadingedge.
 4. A sub-intimal dissector comprising, a. the structure inaccordance with claim 1, in which, b. a portion of the shaft immediatelyrearwardly of the top is sufficiently rigid to prevent significantflexure at the junction of the tip and shaft.
 5. A sub-intimal dissectorcomprising, a. the structure in accordance with claim 1, in which, b.the said opposed side edges are parallel for a relatively short distanceimmediately rearwardly of the said leading edge, c. a portion of theshaft immediately rearwardly of the tip is sufficiently rigid to preventsignificant flexure at the junction of the tip and shaft, and d. the tipis provided with an extremely low friction surface.
 6. A method forperforming endarterectomies comprising: a. incising an artery to exposethe interface between the intima and the media, intruding a dissectingtip intermediate the intima and the media at said exposed interface, c.wedging the intima and media apart by passing the dissecting tiplongitudinally along said interface for a distance from said incisionwhile avoiding damaging the integrity of both the intima and media, d.withdrawing the dissecting tip longitudinally to the incision, e.reintruding the dissecting tip intermediate the intima and media andwedging the intima and media apart as aforesaid successively along pathscontiguous to previous paths of movement of said tip for said distanceuntil substantially the entire intima is wedged from the media alongsaid distance, and f. withdrawing the disengaged intima from the artery.7. A method for performing endarterectomies comprising: a. the procedurein accordance with claim 6 including b. the steps of wedging the intimafrom the media by passing along said interface a dissecting tip having aconcave top surface and a conforming convex bottom surface; the arc ofthe said tip being generally transverse to the longitudinal axis ofmovement of the said tip and extending an arcuate distance equal toapproximately one third to one fifth of the circumference of the artery;the said tip having a slightly forwardly convex leading edge smoothlymerging with opposed side edges; the leading edges and both side edgesbeing smoothly rounded between the top and bottom surfaces.
 8. A methodfor performing endarterectomies comprising: a. the procedure inaccordance with claim 6, and the steps of b. incising the artery toexpose interfaces between the intima and media both distal and proximalto an occlusion, and c. wedging the intima and media apart by passingthe dissecting tip longitudinally along said interface as aforesaid fromboth the distal and proximal incisions in the direction of the oppositeincision until the paths of disengagement from the respective incisionsengage.